1. Field of the Invention
The present invention relates to a safety-start system for an appliance and more particularly, to a clothes dryer making use of such a safety-start system for preventing operation of the dryer unless the safety-start system is intentionally actuated.
2. Description of the Prior Art
Safety dictates that certain domestic appliances be provided with means for preventing the operation of the appliances unless and until the access door associated therewith is in its closed position and a definite step is taken, independent of the closing of the access door, to set the appliance into operation. Generally such a device includes a switch which must be manually actuated upon the closing of the access door of the appliance and usually it is located in a position remote from the door such as on the control panel of the appliance.
The prior art, such as in U.S. Pat. Nos. 2,135,685-Wells; 2,157,112-Bonner; 2,284,026-Stockham; 2,291,088-Morgenstern; and 3,609,265-Garbe et al; disclose safety-start devices for appliances which generally require some sort of rotational movement of a handle or knob on the door to effect actuation thereof to set the appliance in operation.
U.S. Pat. No. 3,133,168-Jacobson, assigned to the same assignee as the present invention, shows safety-start apparatus for a domestic appliance wherein rotation of a handle effects locking of a door and at the same time actuation of a switch for setting the appliance into operation. To open the access door the handle must be again rotated. U.S. Pat. No. 3,602,662-Haller discloses a safety-start device wherein manual depression of a push button, with the access door in the closed position, causes longitudinal positioning of a cam mechanism for effecting actuation of a switch member, the plunger of which moves at right angles to the motion of the pushbutton actuated cam mechanism. U.S. Pat. No. 3,742,162-Wasemann discloses a safety-start device for a laundry appliance wherein the closing of an access door causes the biasing of switch contact in a direction to close them while a blocking member internal to the switch housing prevents the contacts from closing until removed through manually depressing a pin extending through the housing of the laundry appliance. U.S. Pat. No. 3,924,085-Stone, assigned to the same assignee as the present invention, discloses a switch in axial alignment with a manually operated actuating member secured to the access door such that the operational components of the appliance are prevented from operation until actuated by the intentional manual operation of the actuating member. U.S. Pat. No. 3,803,725-Takeyama shows a push button mechanism for starting a clothes dryer.
U.S. Pat. No. 2,858,619-Hughes, assigned to the same assignee as the present invention, discloses a control system for a clothes dryer. Shown therein is a schematic representation of a control circuit including a push-to-start safety switch located on the control panel of the dryer. Included is a door switch operated by the door and a speed-responsive switch operated by the drive motor, the drive motor being arranged in series circuit with the door switch. Once the door is closed, the door switch is also closed and the machine may be made operational by depressing the push-to-start button, and upon the motor coming up to speed, the speed-responsive switch therin is coupled in circuit to bypass the push-to-start button. In other words the push-to-start button is depressed long enough such that the motor will come up to speed to allow the speed-responsive switch to close.
It is desirable to provide a safety-start system for an appliance, such as a domestic clother dryer, that requires supplemental manual effort to actuate after closing of the appliance door, and further in which the door automatically unlatches and the operation of the appliance is terminated upon any circuit interruption and the appliance cannot be restarted without proceeding again through the supplemental manual effort.
By the present invention, there is provided an improved safety-start system useful in an appliance, such as a domestic clothes dryer which is rather simple of construction, highly reliable, efficient, low cost, and easily adapted to any appliance cabinet having a door hinged thereto. The safety-start system of this invention causes, upon actuation, the door to be latched and maintain the appliance in operation and, unlatched upon any circuit interruption such that the door is automatically opened and shut-down of the appliance is effective.